Chapter 6: Difficulties on Theory Summary and Analysis

Four objections may be raised to the theory of natural selection. The first is that, if the species have descended from others by small, gradual changes, there should exist a large number of intermediate, transitional organisms that link the various species together. However, these do not exist. Second, there are many organs and traits of organisms that seem far too complex for natural selection to produce, such as the eye, which is an incredibly complex and fine-tuned organ. Third, how can natural selection account for the complex instincts of animals that are often capable of producing behavior that even humans cannot understand? Finally, according to the theory of natural selection, species are only separated from varieties by degree of difference. However, when varieties are interbred, the offspring is generally stronger and healthier than its parents...